This invention relates to clutches of the type employing an annular or Belleville spring for actuating heavy duty clutches. More particularly, the invention concerns an improved method of manufacturing a collector ring for use with the latter spring, wherein elimination of warpage of the ring is achieved. Such warpage and consequent uneveness of surface is otherwise introduced into the ring during the heat treatment and/or quenching phases of its manufacture. The lack of successful control of hoop stresses imposed during the heating and cooling of relatively thin annular members generally results in the loss of planar quality, wherein portions of such members are not contained within a common plane.
Several attempts have been made to reduce the extent of the problem as related to the manufacture of collector rings; one of such attempts being the heating of stacks of such rings, each loaded against the next, during heating and quenching operations. A principal drawback, however, is that surface hardness is not optimized thereby during the tempering of such rings, as the heating and cooling processes are not uniformly conducted therethrough.
Ideally, each hoop member could be suspended separately, and thus heat treated in a free and unrestrained state without warpage and uneveness of surface; thus maintaining its planar quality as well as having the requisite or desired hardness.